David D. Kaplan looks at a B-24 aircraft for the first time since August 1944 on Friday at Worcester Regional Airport.

WORCESTER — Being a member of the crews that manned the gun turrets of the B-17 Flying Fortresses and the B-24 Liberators that blanket bombed Axis targets in Europe was one of the most perilous assignments that a World War II serviceman could draw.

David D. Kaplan, a 103-year-old retired high school and college music teacher from Worcester, would know.

During the waning months of the war, Mr. Kaplan trained hundreds of men how to operate the deadly twin machine guns that were encased in the four bubble turrets that were attached to the nose, tail, upper fuselage and belly of the jumbo, four-propeller planes.

"In the case where your plane was going down, you'd fall out of the gun turret and hope that the parachute that was attached to you would open up," said Mr. Kaplan. "If it didn't, the Army promised you that it would issue another one the next time around."

This weekend, Mr. Kaplan and his son, Kim Kaplan, joined a number of Central Massachusetts residents at Worcester Regional Airport to visit the "Wings of Freedom Tour" that is being sponsored by the Collings Foundation, an organization that maintains historical war aircraft and vintage automobiles.

The planes displayed on the airport tarmac were the P-51 Mustang fighter; a 1944 Consolidated B-24J Liberator that flew 130 missions, and a Boeing B-17G Flying Fortress, which also took part in countless bombing and reconnaissance missions.

"Seeing those planes did bring back some memories," said Mr. Kaplan, the husband of the late Celia Kaplan.

Mr. Kaplan was a music teacher, who taught for 13 years at North High School and another 15 at the former Classical High School. He was an instructor for a few more years at Newton South High School in Newton before becoming a teacher at the Berklee School of Music and the University of Massachusetts at Lowell.

During the latter years of the war, Mr. Kaplan, who has three children, taught young soldiers at an air base in southern Texas how to shoot the dual machine guns within the close quarters of a plane turret.

The B-17 was a heavy bomber with four engines that was developed in the 1930s for the United States Army Air Corps. The plane, which underwent a number of design changes, was primarily used against German industrial and military targets in daylight raids.

The B-24 had a more modern design, and it had more speed and range than the B-17.

It could also carry more bombs, and, by the end of the conflict, it was the most produced heavy bomber in history, with at least 18,400 units produced.

The planes had a pilot, a co-pilot, a navigator, a radioman, four gun-turret operators, and two other soldiers who fired machine guns from the sides of the craft.

Mr. Kaplan said turret duty was a tough job for servicemen, given the very tight space in which they were encapsulated.

The glass turrets were only 33 inches in diameter.

Mr. Kaplan said the operator had to sit with his head to his knees. The gun controls were overhead.

To make matters worse, crew members had to wear heavy flight suits with oxygen tanks.

Mr. Kaplan said that, given the circumstances, it was difficult to shoot the 50 caliber weapons.

"There was no room to move at all," said Mr. Kaplan, noting that he was about 70 inches in height during the war. "I trained whole sets of men. "We'd get one group ready, and another would come in."

Mr. Kaplan said being a crew member was stressful and many sought to end their lives.

One pilot, for example, took his plane up and then smashed it back down onto a runway.

In addition to anti-aircraft fire from the ground, plane crews often had to cope with the barrage of guns from enemy fighters.

Mr. Kaplan said he was lucky because he never saw combat overseas.

He had been scheduled to go to Europe, but he never made the trip because Germany surrendered shortly after his orders were issued.

Later, it looked as if he would be fighting in the Pacific theater but never got the chance because Japan surrendered.